Key result
Methylnaltrexone significantly increases rescue-free bowel movements within four hours versus placebo.
Why the study?
Constipation is a common adverse effect in patients on long-term opioid therapy, and the efficacy of methylnaltrexone for opioid-induced constipation requires systematic evaluation.
Does methylnaltrexone improve rescue-free bowel movement in patients with opioid-induced constipation?
Meta-Analysis (n=1,239)
Does methylnaltrexone improve rescue-free bowel movement in patients with opioid-induced constipation?
Effect estimate: Risk Difference (95% CI 0.267-0.385)
p-value: p=< 0.0001
Methylnaltrexone significantly increases the likelihood of rescue-free bowel movements within four hours in patients with opioid-induced constipation.
Methylnaltrexone boosts rescue-free bowel movements in OIC; reinforces its efficacy as peripheral antagonist for long-term opioid users.
OBJECTIVE: Constipation is a common adverse effect in patients requiring long-term opioid therapy for pain control. Methylnaltrexone, a quaternary peripheral mu-opioid receptor antagonist, is an effective treatment of opioid induced constipation (OIC) without affecting centrally mediated analgesia. Our objective was to conduct a review and meta-analysis to evaluate the efficacy of methylnaltrexone for treatment of OIC, as well as to provide a clinical discussion regarding newly developed alternatives and provide the current treatment algorithm utilized at our institution. METHODS: We performed a systematic review and meta-analysis of randomized control trials using Cochrane Collaboration Databases and MEDLINE from 2007-present. Literature related to methylnaltrexone, opioids, opioid receptors, opioid antagonists, opioid-induced constipation were reviewed. A meta-analysis was completed with the primary outcome of rescue-free bowel movement (RFBM) within four hours of administration. All pooled analyses were based on random-effects models. RESULTS: 1239 patients were analyzed; 599 received methylnaltrexone and 640 received placebo. With a 95% CI calculated, the true risk difference is between 0.267 and 0.385, demonstrating a statistically significant difference in RFBM between treatment and placebo groups (p < 0.0001). Both the 0.15 mg/kg, 0.30 mg/kg doses every other day, and 12 mg/day dose were found to have increased risk of RFBM compared to placebo. CONCLUSION: Results support the use of methylnaltrexone. Furthermore, the use of methylnaltrexone to induce laxation may decrease use of health care resources, increase work productivity, and improve cost utilization. New treatments have been made available; however, controlled clinical studies are needed to demonstrate long-term efficacy, safety and cost-effectiveness. Possible limitations of this study include the relatively small number of randomized, placebo-controlled trials investigating the efficacy of methylnaltrexone versus placebo. There is also the possibility of publication bias, which may lead to overestimating the efficacy of methylnaltrexone in treating OIC.
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Mehta et al. (2016) conducted a meta-analysis in Opioid-induced constipation (n=1,239). Methylnaltrexone vs. Placebo was evaluated on Rescue-free bowel movement (RFBM) within four hours of administration (Risk Difference, 95% CI 0.267-0.385, p=< 0.0001). Methylnaltrexone significantly increased the likelihood of a rescue-free bowel movement within four hours compared to placebo (risk difference 95% CI 0.267-0.385; p < 0.0001).
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